This invention relates to an engine starter and, more particularly, to an engine starter in which an over-running clutch is moved by a shift lever.
FIG. 1 illustrates in sectional side view a conventional engine starter. The engine starter comprises a d.c. motor 1 having a yoke 2 to which a plurality of magnetic poles 3 are attached. A rear bracket 4 is secured to the rear end of the yoke 2, and a front bracket 5 is secured to the front end of the yoke 2. The rear bracket 4 and the front bracket 5 rotatably support the rotary shaft 7 of an armature 6 through rear and front bearings 8 and 9. The rear bracket 4 also supports a brush assembly 10. The front bracket 5 includes a mounting flange 5a which engages a mounting surface 20a of the engine casing 20 containing an engine ring gear 19. The mounting flange 5a is secured to the mounting surface 20a of the casing 20 through fastener bolts 5c (only one is shown in FIG. 1). The front bracket 5 also comprises a pinion case 5d which fits within an opening 21 formed in the mounting surface 20a of the engine casing 20 and has an inner circumference at a position 5e corresponding to the mounting surface 20a of the casing 20.
Within the front bracket 5, an over-running clutch 11 is axially slidably mounted on the rotary shaft 7. The over-running clutch 11 includes a clutch inner member 12 on which a pinion 13 is integrally formed. Since the clutch inner member 12 is relatively long, two bearings 12a and 12b axially spaced apart from each other are disposed between the clutch inner member 12 and the rotary shaft 7. In order to limit the forward movement of the pinion 13 along the rotary shaft 7, a stopper 14 is disposed on the rotary shaft 7. A flange 11a defines a circumferential groove 11b between the flange 11a and the rear end surface 11c of the over-running clutch 11 for a purpose which will become apparent later.
The starter also comprises a solenoid switch 15 which, when actuated, magnetically attracts a plunger 16 to pull a hook 17 rearward. The hook 17 of the solenoid switch 15 is connected to one end of a shift lever 18 for connecting the solenoid switch 15 to the over-running clutch 11 for axially moving the over-running clutch 11 and the pinion 13 back and forth on the rotary shaft 7 between a rearward position shown by solid lines and a forward position shown by dot-and-dash lines in FIG. 1.
The shift lever 18 comprises an elongated main body 18a, a bifurcated first end portion 18b operatively coupled to the hook 17 of the plunger 16 of the solenoid switch 15, a pivot point 18c pivotally supported between the front bracket 5 and the yoke 2, and a bifurcated second end portion 18d operatively coupled to the over-running clutch 11. The second end 18d of the shift lever 18 has two tines having substantially circular ends 18e which operatively engage the annular groove 11b defined between the flange 11a and the rear end surface 11c of the over-running clutch 11.
When the solenoid switch 15 is energized, the plunger 16 pulls the hook 17 rearwardly to cause the counterclockwise rotation of the shift lever 18 about the pivot point 18c. Then, the shift lever 18 causes the over-running clutch 11 to slide forward along the rotary shaft 7 to bring the pinion 13 on the clutch inner member 12 of the over-running clutch 11 from the rearward position shown by the solid lines to the forward position shown by the dot-and-dash lines, into engagement with the engine ring gear 19. Simultaneously with the forward movement of the pinion 13, movable contacts (not shown) on the plunger 16 of the solenoid switch 15 engage stationary contacts (not shown), whereby an electric power source is connected to the d.c. motor 1 to rotate the motor armature 6 which, through the pinion 13, causes the engine ring gear 19 to be driven to start the engine.
In the conventional engine starter as above described, the engagement opening 21 has a relatively small diameter D and a relatively long distance L between the mounting surface 20a of the engine casing 20 and the engine ring gear 19. Therefore, the inner circumference of the front bracket 5 has a relatively small diameter located close to the shift lever 18, so that the point at which the shift lever 18 is coupled to the over-running clutch 11 cannot be located deep within the pinion case 5d and the clutch inner member 12 of the over-running clutch 11 must have a relatively large axial dimension. The axially elongated clutch inner member or cylinder 12 requires a troublesome precision finishing of the inner surface and two bearings spaced apart from each other, thereby increasing the cost of the starter.